Interlocking plywood sections

[redkic013]

Hi All

I am trying to break into the world of furniture design and have had my first commission; interlocking 24mm plywood sections cut via CNC with a glass surface (images attached). The sections are quite large and slot together as in the red/blue image attached. Understandably I want it to go well so I have the following question.

If the plywood sections are 24mm thick, how wide should the grooves be? Ultimately they will be glued, I understand the groove should be 'slightly wider' than the material but by how much I am unsure
Currently the grooves are modelled to be 24.75mm but I am not sure if this is too much or not enough. Any thoughts or suggestions would be very welcome.

Many thanks in advance

Steve

 

[MikeG.]

Hi All

I am trying to break into the world of furniture design and have had my first commission; interlocking 24mm plywood sections cut via CNC with a glass surface (images attached). The sections are quite large and slot together as in the red/blue image attached. Understandably I want it to go well so I have the following question.

If the plywood sections are 24mm thick, how wide should the grooves be? Ultimately they will be glued, I understand the groove should be 'slightly wider' than the material but by how much I am unsure
Currently the grooves are modelled to be 24.75mm but I am not sure if this is too much or not enough. Any thoughts or suggestions would be very welcome.

Many thanks in advance

Steve

This is what scrap timber is meant for! Cut some trial pieces with varying widths. Personally, with the precision you have available at your fingertips, I reckon you'll need somewhat less than 3/4 of a mm tolerance. If you are gluing these pieces together permanently, then PU glue will fill any over-sized gap. However, if this is a dry fit, then you might want to keep the tolerance down as small as possible, then wax the (pre-finished) pieces before persuading them together with something big and heavy.

Oh, and I reckon your support arms are a little skinny. There might be more flex in that table than you or your client is comfortable with.

 

[MattRoberts]

Ply measurements are nominal, so 24mm ply will actually be less than 24mm, and it will vary slightly per sheet (and even across the same sheet). Your best bet would be to measure the thickness with calipers. How accurate you need to be depends a bit on whether the three sheets are attached anywhere other than those central slots. I assume the are, as the tips aren't likely to stay perfectly separated without support.

If they are attached, then you won't need to worry too much about having a snug fit in the slots

 

[Chrispy]

And to just add to the equation don't forget to allow a bit for cleaning up the faces of the ply before polishing.
although CNC can be very precise there is also a lot of trail and error your material won't be exact and the cutters won't necessarily be what they say either. spirals are often under size when new and of course get smaller when sharpened like any cutter.

 

[Dee J]

Those long intersecting fingers of ply will have little strength... so I think you'll need to aim for a fairly loose assembly. A tight fit in one slot will push the fingers into the adjacent slots, thus narrowing and further tightening the assembly. Perhaps a little artistic licence is needed.... drop the fingers and form one big halving joint instead. Some discreetly placed spacers will keep the layers correctly positioned... and with care the assembled appearance will be indistinguishable from your design.